516 research outputs found
The Housing and Community Development Act of 1992: Affordable Housing Initiatives May Have Found a Home
An analytic interface dynamo over a shear layer of finite depth
Parker's analytic Cartesian interface dynamo is generalized to the case of a
shear layer of finite thickness and low resistivity ("tachocline"), bounded by
a perfect conductor ("radiative zone") on the one side, and by a highly
diffusive medium ("convective zone") supporting an -effect on the other
side. In the limit of high diffusivity contrast between the shear layer and the
diffusive medium, thought to be relevant for the Sun, a pair of exact
dispersion relations for the growth rate and frequency of dynamo modes is
analytically derived. Graphic solution of the dispersion relations displays a
somewhat unexpected, non-monotonic behaviour, the mathematical origin of which
is elucidated. The dependence of the results on the parameter values (dynamo
number and shear layer thickness) is investigated. The implications of this
result for the solar dynamo problem are discussed.Comment: 11 pages, 4 figures Geophys. Astrophys. Fluid Dyn., in pres
An Examination of Enhanced Atmospheric Methane Detection Methods for Predicting Performance of a Novel Multiband Uncooled Radiometer Imager
To evaluate the potential for a new uncooled infrared radiometer imager to detect enhanced atmospheric levels of methane, three different analysis methods were examined. A single-pixel brightness temperature to noise-equivalent delta temperature (NEdT) comparison study performed using data simulated from MODTRAN6 revealed that a single thermal band centered on the 7.68â”m methane feature leads to a detectable brightness temperature difference exceeding the sensor noise level for a plume of about 17âppm at ambient atmospheric temperature compared to an ambient plume with no enhanced methane present. Application of a normalized differential methane index method, a novel approach for methane detection, demonstrated how a simple two-band method can be utilized to detect a plume of methane that is 10âppm above ambient atmospheric concentration and â10âK from ambient atmospheric temperature with an 80â% hit rate and 17â% false alarm rate. This method was capable of detecting methane with similar levels of success as the third method, a proven multichannel method, matched filter. The matched-filter approach was performed with six spectral channels. Results from these examinations suggest that given a high enough concentration and temperature contrast, a multispectral system with a single band allocated to a methane absorption feature can detect enhanced levels of methane
INVESTIGATION OF SOLID PHASE POLYMERIZATION. XL. THE ROLE OF CRYSTALLOGRAPHIC FACTORS IN THE SOLID PHASE POLYMERIZATION OF N-VINYLPHTHALIMIDE
Climate or rural development policy?
Being heavily energy dependent, it is not much of a surprise that Europe pays special attention to reducing the use of fossil fuels. Each one of the ten new member states is characterized by relatively low per capita energy consumption and relatively low energy efficiency, and the share of renewables in their energy mix tends to be low, too. The paper examines the problem when policy measures create a decrease in environmental capital instead of an increase. In this case it hardly seems justified to talk about environmental protection. The authors describe a case of a Hungarian rapeseed oil mill which would not be of too much interest on its own but given that almost all similar plants went bankrupt, there are some important lessons to learn from its survival. The enterprise the authors examined aimed at establishing a micro-regional network. They completed a brown-field development to establish a small plant on the premises of a former large agricultural cooperative. By partnering with the former employees and suppliers of the sometime cooperative, they enjoyed some benefits which all the other green-field businesses focusing on fuel production could not. The project improved food security, energy security and population retention as well
More frequencies of KUV 02464+3239
Preliminary results on KUV 02464+3239, a pulsating DA white dwarf are
presented. Located near the red edge of the DAV instability strip, KUV
02464+3239 shows large amplitude and long period pulsation modes. Up to now
only one mode was known from a 50-minute-long light curve. Our more extended
observations allowed the identification of three additional frequencies. The
presence of previously known harmonics were confirmed and weak subharmonics are
also noticeable at some parts of the light curve. This suggests the dominance
of nonlinear pulsation effects from time to time.Comment: 3 pages, 3 eps figures; has been accepted for publication in
Astronomische Nachrichten (Vol. 8, 2007), proceedings of the
British-Hungarian-French N+N+N Workshop for Young Researcher
Happiness, environmental protection and market economy
The manufacturing sector is leaving the West for Asiaâs low wages and good working culture. Europe would be better off keeping these manufacturing activities, slowing down wage inflation and what is more, letting a young, cheaper workforce from the East settle down within their borders. This would aid in preserving the diverse economic structure which has been characteristic for Europe.Beside the economic growth there are two more concepts which have turned into the âholy cowsâ of economics during the last fifty years. One is the need to constantly improve labor productivity and the other is increasing competitiveness of nations. The high labor productivity of some countries, induces severe unemployment in the globalized world. In the other hand it is high time we understood that it is not competition, but cooperation that brings more happiness to humanity.Should we still opt for âhappinessâ and âsanityâ, it is quite obvious that we all should, in economistsâ terms, define our individual welfare functions corresponding to our own set of values, staying free from the influence of media, advertisements and fashion. The cornerstone to all this is the intelligent citizen who prefers local goods and services
Fault ride-through performance evaluation of an interleaved grid-connected converter employing low switching frequency
A Classification of Single-Phase Transformerless Inverter Topologies for Photovoltaic Applications
© 2018 IEEE. In Photovoltaic (PV) applications, a transformer is often used to provide galvanic isolation and voltage ratio transformations. However, a transformer based inverter is bulky and has high conduction losses, therefore lead to a reduction in the inverter efficiency. To overcome this issue, the transformerless inverter topologies are addressed widely, but the main challenge of a transformerless inverter is common mode issue. Numerous topological modifications with their control and modulation techniques makes them difficult to follow, generalize and highlight the advantages and disadvantages. To address the issue, this paper gives an overview on transformerless inverter and classify them into subsection to discuss the merit and demerit of some of the major topologies. Five subsections based on common mode behavior, voltage clamping and decoupling techniques have been demonstrated (i.e., common ground, mid-point clamping, AC-decoupling, DC-decoupling and AC+DC decoupling). To verify the finding and for general consensus, major transformerless topologies are simulated using PLECS. A general summary is presented at the end to stimulate readers to acknowledge the problems and identify solutions
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